1. Field of the Invention
The present invention relates to a data storage device which can function as a meeting recording system, an interview recording system, or the like, storing data such as conversations from meetings and interviews, images from a meeting or an interview, and related data such as meeting notes and interview notes.
2. Description of Related Art
Conventionally, there have been proposed devices that use digital disks, digital still cameras, videotapes, semiconductor memory, and the like to store and playback data such as conversations from meetings, lectures, interviews, telephones, and videophones, as well as video images, images from monitoring cameras, and the like. Compared to having a reporter manually write down only the important points of the information to be recorded, the use of such data storage devices has the advantage of allowing voices and images to be recorded completely without omissions.
These devices can involve: recording digital signals sent via a computer network onto a storage medium; recording analog input signals from a video camera or a microphone directly to a storage medium; or encoding and converting such analog signals into digital signals.
However, these devices had a problem in that desired sections from the recorded voices or images could not be quickly searched.
To overcome this problem, tape recorders and videotape recorders have been proposed that allow easy searching of important sections by adding check-marks to important sections in the incoming audio signals or incoming image signals.
However, these check-marks only serve to specify the position of important sections. It is not possible to indicate which section of the audio signal or the image signal corresponds to each check-mark. Thus, all the audio or image signals that have been check-marked must be played back to determine the contents. Furthermore, it is also necessary to perform the awkward operation of pressing a button while someone is talking, thus distracting the user from the statement taking place.
For these reasons, there have been proposed devices in which audio signals or image signals that are input continuously are stored and played back so that they are associated with user-input data that has been entered via a pen or a keyboard by the user at selected points in time. By using such devices, the audio signal or the image signal can be recorded while the person making the recording performs pen or keyboard input in the same way that a reporter would take notes. By referring to the entered notes later, the portions of the audio or image signal to be played back can be easily selected and played back.
For example, in Japanese laid-open publication number 7-182365, Japanese laid-open publication number 6-176171, Japanese laid-open publication number 6-343146, ACM CHI '94 Proceedings pgs. 58-64 ("Marquee: A Tool for Real-Time Video Logging") the subject matter of which are incorporated herein by reference, there are proposed devices wherein user-input data is associated with audio signals or image signals by using a time stamp. When the data is to be played back, a piece of user-input data displayed on a screen can be specified, and the audio signals or image signals recorded at the same time as the specified user-input data was recorded, can be played back.
Furthermore, in Japanese laid-open publication number 6-276478, the subject matter of which is incorporated herein by reference, there is a proposed device that uses time stamps to associate the continuous audio signals or image signals with still images from specific points in time indicated by the person making the recording.
In Japanese laid-open publication number 6-205151, the subject matter of which is incorporated herein by reference, there is disclosed a device that records audio signals or image signals while adding an index whenever user input has been interrupted for a fixed period of time. When playback is to be performed, user-input data displayed on a screen can be specified, and the audio signals or image signals from the index section corresponding to the specified user-input data is played back.
However, in the data storage devices disclosed in the aforementioned Japanese laid-open publication number 7-182365, Japanese laid-open publication number 6-176171, 6-205151, ACM CHI'94 Proceedings pgs. 58-64 ("Marquee: A Tool for Real-Time Video Logging"), and Japanese laid-open publication number 6-276478, the audio signals or image signals that are input are recorded in their entirety without compression. Thus, it is difficult to record audio or image signals over a long period of time in limited storage space. This is because an enormous amount of storage capacity is required to be able to record long periods of time-series data such as continuously incoming audio signals or image signals.
Among known methods, there has been proposed a method of continuously compressing audio signals and image signals while storing them in a storage medium as well as a method of storing audio signals that does not record silent intervals. Generally, however, all recorded audio signals and image signals are stored with the same compression ratio. For this reason, it is not possible to have only the important sections played back at high audio/image quality.
For example, when recording sounds and images from a long interview using Video for Windows ("Microsoft Video for Windows 1.0 Users Guide", pp. 57-59, pp. 102-108), the subject matter of which is incorporated herein by reference, the dropped-frame compression ratio can be set to conserve storage capacity by recording only one frame from the image signal every five seconds. When the user later wants to play back sections that were thought to be important during the recording, motions made by the speaker (gestures), mannerisms, and subtle nuances may be lost because only one frame of the image signal was recorded every five seconds. Conversely, if the image signals are recorded at 30 frames per second over the entire interview, the required storage capacity will be very large, and the recording of a long interview would be extremely difficult.
In Japanese laid-open publication number 6-343146, there is disclosed a method for recording signals for a fixed interval based on the timing of inputs from the user. However, in this method, the data that can be played back is rigidly restricted to the signals within the fixed intervals. Thus, for example, if audio and image signals from an interview are being recorded, it would be possible to play back only the audio and image signals within the fixed intervals determined by the timing of inputs from the user. The sounds and images from the portions outside of these fixed intervals cannot be played back at all.
Also, since there is no relation between the sounds and user input, it is possible that the recording could miss the beginning of a statement from the speaker or the recording could be halted before the speaker has finished talking.
In Japanese laid-open publication number 6-153199, the subject matter of which is incorporated herein by reference, there is described a monitoring device which, when a trigger signal from a sensor is detected, a prescribed number of image frames before and after the detection of the trigger signal is recorded. This monitoring camera device stores images in a similar manner as the device described in Japanese laid-open publication number 6-343146, starting at a fixed interval before a trigger signal is detected and ending at a fixed interval after the trigger signal is detected.
However, if sounds and images from an interview are to be recorded with the device, the user inputs (the trigger signal) would be generated at an undetermined period of time after the speaker has begun talking. Thus, even with the monitoring camera device technology described in Japanese laid-open publication number 6-153199, where an interval of a prescribed number of frames before and after a trigger is recorded, the recording may miss the initial portion of the speaker's talking, or the recording could be stopped before the speaker has finished as in Japanese laid-open publication number 6-343146.